Hepatic encephalopathy presents the most serious sequel to liver disease. The seriousness of its occurrence has stimulated many studies of its pathogenesis and treatment. Potentially cerebrotoxic substances which are detoxified by the normal liver would remain, more or less, unchanged in the arterial blood to reach the central nervous system in liver failure. This study investigates the role of short chain fatty acids and alcohols of enteric bacterial origin in hepatic encephalopathy and postulates that therapy directed at lowering SCFA and alcohol production by enteric bacteria will ameliorate hepatic encephalopathy. Oral antibiotic therapy for hepatic coma will be used in an attempt to lower levels of SCFA and alcohols in large bowel contents which will be correlated with serum levels of these substances and changes in encephalopathy. SCFA and alcohols will be determined by gas chromatography and quantitative anaerobic and aerobic bacterial flora of the large bowel by the Hungate roll tube technique.